internal standard

[nina]

Hi
1-I use capric acid (ester)as internal standard in analysis of methyl oleate.
but when the area of analyte increase, area of ISt deacrease or conversely.
I haven't any explanation for it.

2-how do I calculate the response factor?(is it correct: area/amount of analyte)in quantitation analysis,should use the response factor?
please explain for me
thanks in advance

[chromatographer1]

Your results do not appear authentic. I would suggest that you explain your procedure in more detail. Perhaps then a reasonable explanation for your unusual results can be postulated.

[nina]

Hi
internal standard:methyl decanoate
analyte:methyl oleate
column:PEG 20M capillary column,30m,0.22mm id,
carrier gas and make up:He 1.53mm/min
hydrogen and air:30,300 mm/min
det temp(FID):250
inj temp:240
column temp:160,5C/min,230
split ratio:1:50
conc istd:50ppm
thanks

[DR]

You do normal external standard calculations EXCEPT that you use the ratio of your analyte/internal std peaks instead of your analyte area everywhere in the calculations.

[nina]

thanks alot
nina